1. Field of the Invention
This invention relates to sailing craft and in particular to rudder assemblies thereof.
2. Prior Art
Conventionally, rudders of sailing craft have a fixed rotational axis so that when the vessel heels the rudder is, accordingly, canted. Its steering effect varies inversely relative to the heel angle thus requiring increased weather helm as heel increases. When the rudder is canted transversely steering force on the rudder upon application of weather helm is in great measure dissipated as a component of the force of water against the rudder acts upwards and increases drag thus materially reducing the speed of the craft and ultimately does cause the rudder to stall.
A further objection to the use of a fixed rudder post resides in the fact that the rudder offers, at all attitudes of the craft, a fixed frontal area. A rudder disposed with its rotational axis vertical provides optimum steering efficiency which is needed when the craft is heeling on close hauled reaches and under relatively heavy winds, however, when the craft is sailing under light winds and is not excessively heeled or sailing before the wind where steering effect of the rudder is less material the frontal area presented by a vertical rudder post adds material to drag. It is desirable, under the latter conditions, that the rudder post have a rearward sweep -- slightly over 45.degree. being considered acceptable for some types of craft -- so as to thereby decrease the frontal area of the rudder and reduce drag. Designers of sailing craft have, in the past, arrived at a compromise between the two positions and very often mount the rudders so that the rudder and rudder post sweep aft at an angle of approximately 20.degree. to 25.degree. . With the rudder thus disposed, it is not at its optimum with respect to steering efficiency or drag under any sailing conditions.
Rudder assemblies have heretofore been developed which enable the rudder post to be adjustably canted to port or starboard so that the rudder can be disposed in a vertical plane regardless of the attitude of craft. In this type of rudder assembly, as the rudder is vertical, steering effect is optimized requiring less weather helm than in fixed craft. Power loss due to the uplifting effect of a canted rudder is also eliminated. This type of rudder assembly, however, presents a constant front area as is common with fixed rudder assemblies. The transversely cantable rudder assemblies are not suited for use in large sailing craft due to the heavy latteral forces applied to the rudder and thus are heavy and relatively unmanagable unless provided with powered adjusting devices.